This invention relates to an improved method and apparatus for holding and cooling a tube during welding.
Certain problems are encountered while attempting to weld items to a cylindrical metal tube. Because of the heat from the welding, the walls of the tube become warped, thereby causing the tube to have an irregular non-cylindrical shape a considerable distance from the welded portion. This problem is particularly critical in the making of hydraulic cylinders wherein the barrels of the cylinders must be kept round to within very close tolerances.
In present methods for making hydraulic cylinders, the barrel of the cylinder is honed on the inner surface so that the inner cylindrical surface is round to very close tolerances. The couplings for the hydraulic hoses to be used with the cylinders are then welded to the exterior surface of the cylinder barrel. During welding, the barrel becomes warped and loses its round configuration in the vicinity where the welding occurred. It is therefore necessary to rehone the interior of the cylinder after the welding is finished in order to have a cylindrical round surface for receiving the cylinder piston.
Therefore, a primary object of the present invention is the provision of an improved method and apparatus for holding and cooling a metal cylinder during welding.
A further object of the present invention is the provision of a method and apparatus which permits the tube to be maintained in a true, round shape throughout the welding process.
A further object of the present invention is the provision of a method and apparatus which minimizes the tendency of the tube to warp during welding.
A further object of the present invention is the provision of a method and apparatus which eliminates the need to rehone the interior surface of the cylinder after welding.
A further object of the present invention is the provision of a method and apparatus which keeps the barrel cool enough during welding to minimize oxidizing of the metal in the cylinder barrel.
A further object of the present invention is the provision of an apparatus having a mandrel positioned in the interior of the barrel and being expandable in a uniform manner along its entire length, so as to press outwardly against the inner surface of the barrel with a uniform pressure along the entire axial length of the mandrel.
A further object of the present invention is the provision of an apparatus and method which permits the use of cooling fluid to carry heat away from the area where welding occurs.
A further object of the present invention is the provision of a device which is economical to manufacture, durable in use and efficient in operation.